Electronic power devices particularly intended for rail traction usually comprise a conductive substrate made of copper, for example, to which are attached composite conductor-insulator-conductor structures having a heat transfer and electrical insulation function. The conductive top layer of each composite structure constitutes a substrate on which diodes and insulated gate bipolar transistors (IGBT) are disposed in an arrangement that varies with the nature of the electronic device concerned. The power semiconductor circuits are fixed by tin-lead or tin-lead-silver soft solder.
The free faces of the diodes and the IGBT are covered by one or more connecting terminals to each of which are soldered aluminum wires which typically have a diameter in the order of 380 to 500 microns. The other end of each wire is soldered to the top conductive substrate of one of the composite structures forming an inverter arm.
The above design, which is well-known in the art, has some drawbacks, however. The above power electronic devices are complex to manufacture because they include a very large number of aluminum wires. Also, the overall surface area of these power devices is relatively large, which increases the overall volume of the assembled device and also causes spurious inductance phenomena which compromise its electrical operation.